What is a pre-condition in programming?

A pre-condition in programming specifically refers to a condition that must be true before a piece of code is executed. It establishes the necessary requirements or assumptions that are expected to hold before a function or method runs correctly. For instance, if a function is designed to compute the square root of a number, a pre-condition might be that the input must be a non-negative number. Checking pre-conditions helps to ensure that the program behaves as expected and reduces the likelihood of errors during execution.

The other potential answers describe different concepts: a state that must be met after execution refers to post-conditions, which define the expected state after a function has completed. A condition that is never checked is not applicable, as pre-conditions are specifically meant to be verified. Lastly, a type of loop does not relate to the concept of pre-conditions; it is a programming structure for repeated execution based on a condition. Thus, the definition aligns precisely with the role of pre-conditions in ensuring program correctness before executing code.